Care of the Professional Voice

A Guide to Voice Management for Singers, Actors and Professional Voice Users

D. Garfield Davies, Anthony F. Jahn

• Publisher: Routledge
• Year: 2004
• ISBN:
  9781136799334
• Edition: 2
• Topic: Media & Performing Arts
• Subtopic: Performing Arts

Singer and actors are a unique group of performers, relying almost entirely on their voice for the professional livelihood. Jet lag, amplification, allergens, stress, pollution, and vocal strain all affect vocal performance. Written for the performer, the teacher, and the vocal coach, Care of the Professional Voice offers clear explanations and medical advice on vocal problems and vocal health.

Care of the Professional Voice is written by experts in laryngology in the United States and Great Britain. This second edition includes a singer's guide to self-diagnosis.

ONE

Anatomy and physiology of the vocal mechanism

WHEN WE consider the anatomical parts relevant to the voice, we naturally think of the larynx. The larynx, or voice box, is a highly specialized organ which is perched on top of the trachea (windpipe), and acts as the sound generator during phonation or singing. There are, however, other equally important anatomical structures above and below the larynx, without which the voice could not be produced. These include the mouth, the palate, the pharynx and the lower airway (trachea, bronchi and lungs), as well as the abdomen and even the pelvis. In fact, there are only a few parts of the body not involved in some way in the process of voice production.

Let us now consider the entire vocal tract, and follow the voice’ from its beginnings to its full formation.

The thorax and abdomen

The energy powering the voice is air which is exhaled from the lungs. The lungs are passive bellows within the thoracic cage, which inflate on inspiration and deflate on expiration. The thoracic cage is a rather rigid compartment with a flexible floor: the diaphragm. This thin partition of muscle and fibrous tissue forms a dome which is convex upward (thoracic aspect), and concave downward (abdominal aspect) (Plate 1). As the diaphragm contracts, it flattens, and pulls down towards the abdomen. This has the effect of decreasing the pressure in the thorax and increasing it in the abdomen. Negative thoracic pressure draws air in through the trachea into the lungs: when we breathe in, our lungs fill with air, and our abdomen normally protrudes. This is called abdominal breathing. It is also possible to increase the volume of the thorax by moving the ribs up and down. The ribs, which are hinged to the vertebrae, are connected to each other by smaller (intercostal) muscles. The rib cage is also connected to the collar-bone (clavicle) and the neck muscles. Using these muscles allows the ribs to move to a small degree. This type of breathing, thoracic breathing, is less effective, more effortful, and generally not used in proper vocal technique. A comparison of breathing techniques among actors revealed that the accomplished actor uses more abdominal breathing, and that this abdominal breathing shows greater variation and control, than in his novice actor counterpart.

The abdomen also plays a significant role in voice production. During inhalation, as the diaphragm contracts and descends, the abdominal cavity is compressed and its contents protrude. The muscles of the abdominal wall relax to accommodate this compression. Exhalation during quiet breathing is passive, as the contracted diaphragm relaxes, and the abdominal contents expand to exert upward pressure. During singing and dramatic vocalization, however, exhalation is controlled and active: the muscles in the abdominal wall (the recti and the obliques) contract, pushing the abdominal contents up against the diaphragm. The effect is that of pushing in the plunger of a syringe: air is expelled at a controlled rate of flow through the glottis (laryngeal aperture). The muscles which act in concert then are: the diaphragm, contracting during inhalation, and the abdominals, during exhalation. It is worth emphasizing that the diaphragm is capable of only one active movement, which is contraction (descent). During exhalation and voice production the diaphragm does not contract, and is only a passive partition. Many singers are not aware of this fact, and fancifully attribute the act of breathing to other mechanisms. When asked about the breathing mechanism, one singer spoke about the passive descent of the diaphragm which resulted from air entering the lungs. Many singers image the act of inspiration as a passive event, allowing the air to enter’, or ‘letting the air fall into the lungs’. All of these images are physiologically incorrect.

When expiration occurs, the diaphragm is flaccid, and is passively pushed up by the contents of a contracting abdominal cavity. Supporting the voice from the diaphragm’ is therefore a concept with no anatomical basis. Support of the voice actually comes from the abdominal muscles, rather than the diaphragm.

This in-and-out movement is most effective when the supporting structures do not move. These structures, the pelvis and the back, provide points of attachment for the muscles of respiration, and must be held immobile for optimal respiratory movements.

General muscle tone

The degree of muscular activity in parts of the body not directly involved in respiratory movements is also important. Tension in any muscle group heightens the tension in all other groups, leading to tightness, strain and less effective voice production. Tension in the neck, lower back or even the limbs heightens the tone in muscles directly involved in singing, increasing the effort and decreasing efficiency. Part of the singer’s art is to develop conscious control of postures and movements which are normally reflexive, and exert that control in isolating muscles which must contract, muscles which must relax, and muscles which must be in a state of effortless tone.

Techniques such as Alexander and Feldenkrais are helpful in developing conscious awareness of posture and movement.

Phonation and singing

Vowel sounds are produced when the airstream is continuous; consonants by more or less complete interruption of the stream by interposition of various parts of the tongue, teeth and lips. Singing, for the most part, consists of long phrases and emphasizes vowels. Speech, particularly conversation rather than declamation, emphasizes consonants. The contrast is especially marked if, for example, Russian and German are considered rather than Italian and French – which is one of the reasons why the latter are easier to sing.

The larynx

As mentioned, the larynx is the sound generator on which most interest has been focused. The larynx evolved originally not as the organ of phonation, but as a sphincter which protects the lower airway during swallowing. The larynx is divided into three parts: the glottic part, referring to the true vocal folds; the subglottic part, referring to the area below the glottis; and the supraglottic part, referring to the structures above the vocal folds.

The main structures of the laryngeal framework are the thyroid cartilage and the cricoid cartilage. The thyroid cartilage of the larynx has a triangular shape. The two sides are formed of rigid cartilage and meet anteriorly to form a keel. The top of this keel, called the thyroid notch, can be seen and felt as the Adam’s apple (Plate 2). The two wings (alae) of the thyroid cartilage flare posterolaterally, and are open across the back. The thyroid cartilage rests on a rigid ring of cartilage, the cricoid cartilage. The thyroid cartilage hinges on the cricoid on both sides, and can swing up and down, much like the visor of a knight’s helmet. Unlike the thyroid, the cricoid forms a complete and rigid ring around the upper end of the trachea. It is flattened posteriorly and rounded anteriorly, like a signet ring (Plate 2).

The thyroid and cricoid cartilages constitute the main ‘skeleton’ of the larynx. The cricoid is attached to the first ring of the trachea by fibrous tissue which allows for both strength and some flexibility.

As already mentioned, the larynx’s importance for survival rests on its function as a protective sphincter. Protection of lungs from saliva, food, liquid, and other ingested material is in fact so vital, that there is not one but three different sphincters within the larynx. The lowest, immediately above the cricoid, is formed by the true vocal folds (cords). These are thin slips of muscle and a ligament, covered by mucous membrane, which attach to the inside of the thyroid keel anteriorly (Plate 3). Posteriorly, each vocal fold attaches to an arytenoid cartilage. The arytenoids are tiny jug-shaped cartilages which sit on either side on top of the flattened cricoid lamina (Plate 2). They are controlled by fine muscles, which allow them to swivel apart or together, slide toward each other, and tip forward (Plate 5). The airway between the vocal folds is called the glottis, or glottic aperture, and is like an isosceles triangle in cross-section. Its equal sides are formed by the vocal folds, and its base by the muscle and soft tissue between the arytenoids. The apex of the triangle is formed by the anterior commissure where the vocal folds are attached to the inner surface of the thyroid cartilage. When the arytenoids swivel or pull apart (abduction), the base of the triangle widens, and the airway opens. When the arytenoids come together (adduction), the base of the triangle narrows. When the arytenoids (and the attached vocal folds) are progressively adducted, the airway narrows to a slit, and becomes completely closed. It is in this adducted position that phonation occurs, and this will be discussed at length later (Plate 5).

Above each vocal fold is a broader fold of mucous membrane, the false vocal fold (cord). As the name implies, the false vocal folds look a bit like the true folds, but are not normally ‘vocal’, i.e. involved in phonation. The false folds are not only attached to the arytenoids, but also contain some muscle, which allows them to contract. They lack the fine control of the true folds, but can be squeezed together, along with the true folds, to protect the airway. They thus form the second set of sphincters which protects the lungs. The false and true vocal folds in cross-section look like shelves which project in towards the centre of the airway. They are separated by a small pouch, or pocket, called the laryngeal ventricle. The ventricle, and especially its anterior recess (saccule) is lined with mucus-producing glands which lubricate the vocal folds. In humans, this ventricle has no role in phonation, although in some lower animals (like frogs, apes and monkeys) it can be inflated and act as a resonator or additional air source during phonation.

The third, and highest, laryngeal sphincter is formed by the epiglottis (Plates 2 and 3). This floppy, petal-shaped cartilage is attached at its base to the inner surface of the thyroid cartilage. The rounded petal portion projects up toward the base of the tongue. Its sides are connected by mucous membrane and some muscle fibres to the tips of the arytenoids behind and below it. These folds (aryepiglottic folds), along with the epiglottis in front and the arytenoids in the back, encircle the airway. During swallowing, the epiglottis tips back, like the lid of a box; the aryepiglottic folds and arytenoids pull toward the centre of the airway, and together they close off the top of the larynx. By this mechanism, not only is the airway protected, but channels open up on either side of the epiglottis which allow the swallowed material to flow around the larynx posteriorly, and arrive behind the cricoid, at the upper end of the food passage (oesophagus). This constitutes the third, or supraglottic, sphincter.

Of equal importance to the protective action of these sphincters during swallowing is the powerful upward sliding movement of the entire larynx and attached trachea. This upward motion tucks the larynx close behind the base of the tongue, and under the epiglottis. A set of muscles, which suspend the larynx from the hyoid bone and the jaw allow this elevation to take place (Plate 4). After swallowing, the larynx moves back down to its resting position in the neck. In keeping with the overriding importance of airway protection, the muscles which pull the larynx down (depressors) are not as powerful as those which raise it (elevators). This is somewhat analogous to the powerful muscles which close a crocodile’s jaw, versus the weaker ones which open it. The significance of this fact becomes apparent to singers and actors who are untrained, or performers vocalizing with a great deal of muscular tension. Since laryngeal elevators overpower laryngeal depressors, these singers will often sing with a high larynx. Both externally and internally, the characteristic laryngeal posture caused by excessive muscle tension will reflect the domination of stronger muscles over weaker ones.

The larynx thus far has been described as a sphincter. It protects the lower airway during swallowing by elevating toward the back of the tongue, and closing, bringing together the triple valves of the true folds, the false folds and the supraglottic structures. How does this guardian of the lower airway produce voice? The larynx, as already mentioned, is an organ which can open or close. With the vocal folds (glottis) in the open position (Plate 6), it allows the free flow of air to the lungs during respiration. In the closed position, it protects the airway, and allows the diversion of ingested food and liquid posteriorly, into the oesophagus. This closure is usually instantaneous, reflexive and momentary, coinciding with swallowing. It is also possible to close the larynx voluntarily. In this situation, the vocal folds are forcibly held together, and air pressure in the lower airway is increased by pushing the abdominal contents and the diaphragm up. This pushing against a closed glottis (the Valsalva manoeuvre) facilitates certain actions, such as lifting and straining.

The subglottic air pressure can be increased as long as the vocal folds are held together. Once the air pressure is greater than the force adducting the folds, the folds will be pushed apart, and air will flow through the larynx. Phonation (and singing) consists of balancing the addudive force on the vocal folds, and the subglottic air pressure. These are balanced so closely that as air pushes the vocal folds apart, decreasing subglottic pressure, the vocal folds immediately return to the closed position. Air pressure again builds up until the folds are blown apart. This repeated process results in tiny puffs of air which set the vocal folds vibrating. The folds are not like stiff reeds, but rather like a trumpeter’s lips, which are held under some muscular tension, but open and close rapidly, creating a buzzing sound. In this way, the voice is formed. The frequency of the vocal fold vibration determines the pitch of the sound.

This phenomenon is similar for speech, singing, and other vocal utterances. The main difference lies in the fact that singing involves a more prolonged and sustained voice production, while speech is usually a series of transient sounds.

The normal pitch range of vocalization means that the vocal folds must vibrate hundreds of times per second. They are uniquely suited for this extremely rapid and fine movement by their layered structure. The substance, or body, of the vocal fold consists of the thyroarytenoid (vocalis) muscle, which stretches between the arytenoid cartilage posteriorly and the inner surface of the thyroid cartilage anteriorly. This muscle can actively contract and relax, and can be also stretched passively by muscles which move the cartilages to which it is attached (cricothyroid and cricoarytenoid muscles) (Plate 3). The vocalis muscle is rather bulky, and certainly not capable of rapid and minute oscillations. However, the cover of the vocal fold, consisting of a thin layer of mucous membrane, is. This is possible due to the loose and slippery attachment of this covering membrane to the underlying vocal ligament and muscle. This loose attachment, consisting of a gelatinous microlayer (Reinke’s space), allows the mucous membrane to slide freely in response to air flow, while the vocalis muscle is held in position. The rapid and regular volley of air puffs (up to over 1000 times a second), creates a wave-like to-and-fro rolling of the mucosal cover: the folds are blown apart, slide back together, and are blown apart once more. The coming together of the edges is the result of two forces: once air has escaped through the glottis, the subglottic air pressure is temporarily decreased, and the approximating muscular forces of the larynx are temporarily dominant. The rapid flow of air between the edges itself creates a force (Venturi effect) which pulls the free edges towards each other. Once the glottis is closed, subglottic air pressure again builds up, and the cycle repeats. Although this takes place much faster than the eye can discern, it can be visualized by high-speed photography, or by stroboscopy.

Muscular control of vocal fold tension is complex, and involves several muscle groups acting in fine coordination. These muscles are classified as extrinsic and intrinsic. Extrinsic muscles (Plate 4) connect the larynx to adjacent supporting structures such as the hyoid bone and sternum, whereas intrinsic muscles (Plate 5) connect one part of the larynx to another. Different groups of muscles are used in producing the full vocal range. The lower part of the soprano voice, called chest register, is determined primarily by tension in the vocalis and arytenoid muscles. The upper part, or head voice, is controlled by the cricothyroid muscle, which tilts the thyroid cartilage forward, stretching and thinning the lips of the vocal folds. The transition from one mode of muscle activity to the other (chest to head voice) is awkward, and must be smoothly executed. This ‘break’, called the passaggio, usually occurs at E-F above middle C. The smooth and effortless transition through the passaggio without loss of range, resonance or flexibility must be learned, and is the hallmark of technical mastery. The natural break in the voice which reflects a change in muscle activity is sometimes accentuated for effect, such as seen with yodelling.

Paradoxically, the phonatory movements of the larynx are exactly opposite to its protective actions. For good singing, the larynx must be lowered, not raised, and the supraglottic areas kept open, approximating only the true vocal folds. Rather than squeezing the vocal folds together in a reflexive ‘all-or-nothing’ fashion, the singer must bring them together with a high degree of sensitivity and control, balancing the approximation against the pressure of the air being pushed out from the lungs. From the laryngeal point of view, good singing is a rather unnatural function!

The supraglottic larynx and pharynx

So far, we have examined the power source (lungs) and sound generator (larynx) involved in the voice. In many ways, however, the most important component of voice formation lies in the structures above the larynx.

When the newly-formed voice leaves the vocal folds, it h...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• List of Illustrations
• Forewords by Bryn Terfel, James Morris & Sir Anthony Hopkins
• Acknowledgements
• Preface
• 1 Anatomy and physiology of the vocal mechanism
• 2 Development of the larynx and the voice
• 3 Age and voice
• 4 Attributes of a good vocal performer
• 5 General considerations before performance
• 6 Laryngeal disorders: diagnosis, treatment and prevention
• 7 Anxiety, artistic temperament and the voice
• 8 Popular music and the musical theatre
• 9 Travel and the vocal performer
• 10 Medications and the professional voice
• 11 General medical considerations in the vocal performer
• 12 A visit to the laryngologist
• 13 Surgery and the vocal artist
• 14 A singer’s guide to self-diagnosis
• Suggested reading
• Glossary
• Index